Bone Compression and Fixation Devices

ABSTRACT

A bone screw, for drawing first and second bone fragments together, includes a shaft having a distal section and a proximal section. The distal section has a first external male screw thread and a minor diameter. The proximal section has a second external male screw thread. A major diameter of the distal section is larger than a major diameter of the proximal section. The bone screw includes a sleeve that has an internal female screw thread configured to mate with the second male screw thread. A distal portion of the sleeve has an outer diameter. The outer diameter is equal to or smaller than the minor diameter of the distal section of the shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/417,985 filed Nov. 30, 2010 entitled “CompressionScrew” and U.S. Provisional Patent Application No. 61/417,981 filed Nov.30, 2010 entitled “Flexible to Rigid Bone Fixation Device”, both ofwhich are incorporated by reference herein in their entirety. U.S.Provisional Patent Application No. 61/415,953 filed Nov. 22, 2010entitled “Compression Wire” is also incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION

The present invention generally relates to bone compression and fixationdevices and in some particular embodiments, orthopedic devices forjoining together in compression two or more pieces of a fractured bonefor optimum healing.

BRIEF SUMMARY OF THE INVENTION

In one embodiment there is a bone screw for drawing first and secondbone fragments together comprising a shaft having a distal section and aproximal section, the distal section having a first external male screwthread and a minor diameter, the proximal section having a secondexternal male screw thread, a major diameter of the distal section beinglarger than a major diameter of the proximal section; and a sleevehaving an internal female screw thread configured to mate with thesecond male screw thread, a distal portion of the sleeve having an outerdiameter, the outer diameter being equal to or smaller than the minordiameter of the distal section of the shaft.

In one embodiment, the sleeve is configured to receive a tool to rotatethe shaft and sleeve together when the shaft is driven into a first bonefragment or rotate the sleeve relative to the shaft to draw a secondbone fragment toward the first bone fragment. In one embodiment, a pitchof the first external male screw thread is larger than a pitch of thesecond external male screw thread.

In one embodiment, the distal portion of the sleeve is tapered. In oneembodiment, the sleeve includes two or more external longitudinallyextending slots configured to engage a tool.

In one embodiment, the distal portion of the sleeve is smooth. In oneembodiment, the shaft is cannulated. In one embodiment, the shaftincludes at least one aperture along a length of the shaft in fluidcommunication with a hollow center of the shaft. In one embodiment, theshaft includes a plurality of apertures along a length of the shaft, theplurality of apertures being in fluid communication with one another.

In another embodiment, there is a bone screw system for drawing firstand second bone fragments together, comprising: a bone screw including:a shaft having a distal section and a proximal section, the distalsection having a first external male screw thread, the proximal sectionhaving a second external male screw thread, a major diameter of thedistal section being larger than a major diameter of the proximalsection; and a sleeve having an internal female screw thread engageablewith the second male screw thread, the sleeve being configured toreceive a first tool for rotating the shaft and sleeve together and asecond tool for rotating the sleeve relative to the shaft; a toolincluding: a first tool portion configured to rotate the sleeve relativeto the shaft; and a second tool portion configured to rotate the shaftand the sleeve together.

In one embodiment, the second tool portion includes a threaded distalend that is engageable with the internal female screw thread and abutsthe proximal section. In one embodiment, the second tool portion extendsthrough the first tool portion when rotating the shaft and sleevetogether and the second tool portion is withdrawn from the first toolportion when rotating the sleeve relative to the shaft.

In another embodiment, there is a wire device for drawing first andsecond bone fragments together, comprising: a wire having an externalmale thread; and a sleeve having an internal female thread configured tomate with the external male thread. In one embodiment, the sleeve isconfigured to slide over the external male thread in a distal directionwithout rotating the sleeve relative to the wire. In one embodiment, thesleeve includes two or more axially extending slots to form two or morephalanges. In one embodiment, the wire includes a distal section and aproximal section, the distal section having a first external male screwthread, the proximal section having a second external male screw thread,a major diameter of the distal section being larger than a majordiameter of the proximal section.

In one embodiment, a pitch of the first external male screw thread islarger than a pitch of the second external male crew thread. In oneembodiment, the sleeve includes two or more radially extendingprojections. In one embodiment, a distal portion of the sleeve has adiameter equal to or smaller than a minor diameter of the wire. In oneembodiment, the sleeve is tapered.

In another embodiment there is a method for drawing first and secondbone fragments together, comprising: screwing a wire having an externalmale thread into a first bone fragment; sliding a sleeve having aninternal female thread configured to mate with the external male threadalong the wire without rotating the sleeve relative to the wire to abuta second bone fragment; rotating the sleeve relative to the wire to drawthe second bone fragment toward the first bone fragment, a proximalportion of the wire extending proximally from the second bone fragmentand the sleeve; and cutting and removing the proximal portion of thewire from the remainder of the wire.

In another embodiment there is a bone fixation device comprising: adistal end configured to attached to a first bone section and a proximalend configured to attached to a second bone section, a flexible bodysecured to the distal end and movably attached to the proximal end; anda plurality of cannulated rigid segments surrounding the body, whereinthe segments are spaced and allow the body to flex when the body is in afirst position relative to the proximal end and wherein the segmentsabut and prevent the body from being flexed when the plate is moved fromthe first position to a second position relative to the proximal end.

In one embodiment, the body is flexible along a first plane and rigidalong a second plane, the first plane being orthogonal to the secondplane. In one embodiment, the body has a rectangular cross section. Inone embodiment, the body is threadably attached to a radially rotatable,axially fixed sleeve in the proximal end. In one embodiment, eachsegment includes a projection that mates with an indent of an adjacentsegment in the second position. In one embodiment, the segments arecylindrically shaped. In one embodiment, the body includes at least oneaperture and the proximal end includes at least one aperture, the atleast one aperture of the body aligning with the at least one apertureof the proximal end in the second position.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofembodiments of the bone compression and fixation devices, will be betterunderstood when read in conjunction with the appended drawings ofexemplary embodiments. It should be understood, however, that theinvention is not limited to the precise arrangements andinstrumentalities shown.

In the drawings:

FIG. 1A is a perspective view of a bone screw device in accordance withan exemplary embodiment of the present invention;

FIG. 1B is cross sectional perspective view of the bone screw deviceshown in FIG. 1A;

FIG. 1C is cross sectional side view of the bone screw device shown inFIG. 1A;

FIG. 2A is a perspective view of a tool for implanting a bone screwdevice in accordance with an exemplary embodiment of the presentinvention;

FIG. 2B is a perspective view of the tool shown in FIG. 2A;

FIG. 2C is a perspective view of a distal end of a sleeve of the toolshown in FIG. 2A;

FIG. 2D is a cross sectional perspective view of the tool shown in FIG.2A;

FIG. 3A is a side elevational view of the bone screw device shown inFIG. 1A with a tool in accordance with an exemplary embodiment of thepresent invention;

FIG. 3B is a cross sectional view of the bone screw device and toolshown in FIG. 3A;

FIG. 3C is an enlarged cross section view of the bone screw device andtool shown in FIG. 3B;

FIG. 4A is a perspective view of the bone screw device and tool shown inFIG. 2A in an initially engaged position;

FIG. 4B is a cross sectional perspective view of the bone screw deviceand tool shown in FIG. 4A;

FIG. 4C is a perspective view of the bone screw device and tool shown inFIG. 4A in a fully engaged position with lock sleeve over the driverphalanges;

FIG. 5A is a side elevational view of a bone wire device in accordancewith an exemplary embodiment of the present invention;

FIG. 5B is an outline of a cross sectional view of the bone wire deviceshown in FIG. 5A;

FIG. 6A is a side elevational view of the bone wire device shown in FIG.5A between first and second bone fragments in an engaged position;

FIG. 6B is a side elevational view of the bone wire device shown in FIG.6A in a compressed position;

FIG. 7 is a perspective view of a bone fixation device in accordancewith an exemplary embodiment of the present invention shown in a rigidconfiguration;

FIG. 8A is a perspective view of the bone fixation device shown in FIG.7 with the plurality of segments removed;

FIG. 8B is a perspective view of the bone fixation device shown in FIG.8A with a fixation sleeve attached to the proximal end;

FIG. 9A is a cross sectional side view of the bone fixation device shownin FIG. 7 in a rigid configuration; and

FIG. 9B is a cross sectional side view of the bone fixation device shownin FIG. 7 in a flexible configuration.

DETAILED DESCRIPTION OF THE INVENTION

In orthopedic surgery it is common to rejoin broken bones. However, inmost situations where cross-fixation of the bone fragments is required,the success of the surgical procedure depends to a large extent on thedegree of compression that can be achieved between the bone fragments.More specifically, if the surgeon is unable to bring the bone fragmentsin close contact with each other, there will exist a space or void intowhich the bone tissue must grow before the healing process is complete.Thus, the greater the distance between the bone fragments, the slowerthe healing process. In addition, the healing process can be retarded byany relative movement or shifting of the bone fragments which disturbsthe bone tissue that has been laid down.

Screws commonly used in fracture fixation are of the lag type, andcomprise a threaded leading end and an enlarged head incorporating ameans to engage a driving tool at the trailing end. In some situations,the presence of a screw head has a deleterious effect on the outcome ofthe repair, specifically in cases where the screw must be inserted in ornear a skeletal joint or where inadequate bone stock is available toallow countersinking of the screw head.

Typical headless compression screws, such as the Hubert Screw whichachieves compression by providing two different thread pitches, onepitch toward a distal end an a different pitch toward a proximal end.Apart from being technique sensitive, the ability to compress the bonesegments together with a Hubert Screw is based on the number of threadsin the head. This allows for limited amount of compression. In somesituation, a screw head is desirable but the head contacts the outersurface of the bone at the wrong time to provide the desiredcompression.

In some exemplary embodiments of the present invention, a screw device10 includes a two piece construction that allows for improvedcompression between bone fragments. Though screw device 10 may be usedwith any bone fragments, in some embodiments, screw device 10 isconfigured for use with the small bones of the hand or foot. Anydimensions specifically mentioned below may be varied in someembodiments to accommodate a particular anatomy.

Referring to FIGS. 1A-1C, screw device 10 includes a shaft 12 and asleeve 18 that is movable along the shaft 12 to draw together at leasttwo bone fragments.

In one embodiment, shaft 12 has a distal section 12 a and a proximalsection 12 b. In one embodiment, the distal end of distal section 12 ais pointed. In other embodiments, the distal end of distal section 12 ais generally blunt. In one embodiment, a major diameter of distalsection 12 a is larger than a major diameter of proximal section 12 b.In other embodiments, the major diameters of distal section 12 a andproximal section 12 b are equal. In one embodiment, the major diameterof distal section 12 a and proximal section 12 b are approximately 2.5mm to approximately 10 mm. In one embodiment, the length of screw device10 is approximately 10 mm-approximately 60 mm.

In one embodiment, distal section 12 a includes a first external malescrew thread 14. In one embodiment, proximal section 12 b includes asecond external male screw thread 16. In one embodiment, first externalmale screw thread 14 is configured to engage cortical and/or cancellousbone. In one embodiment, second external male screw thread 16 aremachine threads configured to mate with sleeve 18 and allow the sleeveto travel down the length of shaft 12 as discussed below. In oneembodiment, a pitch of first external male screw thread 14 is largerthan a pitch of the second external male screw thread 16. In oneembodiment, the pitch of first external male screw thread 14 isapproximately 1 mm and the pitch of second external male screw thread 16is approximately 0.45 mm. In other embodiments, the pitch of firstexternal male screw thread 14 is equal to the pitch of second externalmale screw thread 16.

In one embodiment, shaft 12 is cannulated. In one embodiment, the entireshaft 12 is cannulated (bore 12 f) such that both ends of shaft 12 areopen and in fluid communication with one another. In one embodiment,shaft 12 is cannulated axially to allow screw device 10 to be drivenover a guide wire. In one embodiment, the diameter of bore 12 f isapproximately 2.6 mm. In one embodiment, the diameter of bore 12 f isapproximately 1 mm or larger. In other embodiments, only a portion ofshaft 12 is cannulated and/or one or more of the ends are closed. In oneembodiment, shaft 12 includes at least one aperture 12 c along a lengthof shaft 12 and in fluid communication with a hollow center of shaft 12.In one embodiment, shaft 12 includes a plurality of apertures 12 c alonga length of shaft 12, apertures 12 c are in fluid communication with oneanother. In one embodiment, apertures 12 c align with a correspondingdiametrically opposed aperture 12 c. In one embodiment, apertures 12 chave a corresponding opposed aperture 12 c on the opposite site of shaft12 that is at an angle relative to the longitudinal axis of shaft 12. Inother embodiments, apertures 12 c do not have a corresponding aperture12 c on the opposite side of shaft 12. In one embodiment, apertures 12 care approximately 0.2 mm in diameter. In other embodiments, apertures 12c are larger than 0.2 mm in diameter. In one embodiment, apertures 12 care circular. In other embodiments, apertures 12 c are any shapeincluding triangular, rectangular or oval.

In one embodiment, apertures 12 c and/or cannulated shaft 12 allow forfluid such as blood to vascularize the fracture site and aid in fracturehealing. In one embodiment, apertures 12 c and/or cannulated shaft 12allow for fluid to exit the body while implanting screw device 10 ratherthan cause a buildup of pressure within the body. In other embodiments,apertures 12 c and cannulated shaft 12 may be used to deliver a drugsuch as gentamicin or a bone graft through or from within screw 12 tothe fracture site.

In one embodiment, the proximal end of shaft 12 includes a keyed surface12 d. In one embodiment, keyed surface 12 d is a slot. In oneembodiment, keyed surface 12 d is configured to engage a driver tool toprovide counter torque or to drive shaft 12 directly if necessary.

In one embodiment, sleeve 18 threadably mates with proximal section 12 bof shaft 12. In one embodiment, sleeve 18 includes an internal femalescrew thread 20 that is configured to mate with second external malescrew thread 16. In one embodiment, the length of sleeve 18 isapproximately 7 mm.

In one embodiment, sleeve 18 is tapered toward distal section 12 a. Inone embodiment at least a portion of sleeve 18 is frustoconical inshape. In one embodiment, an outer surface of at least a distal portionof sleeve 18 is smooth. In one embodiment, the outer surface of at leasta distal portion of sleeve 18 is void of threads. In one embodiment, theouter diameter of at least a portion of the distal portion of sleeve 18is approximately equal to or smaller than the minor diameter of distalsection 12 a of shaft 12. In one embodiment, the diameter of sleeve 18is greater than the minor diameter of distal section 12 a of shaft 12and tapers toward distal end 18 a to a diameter less than the minordiameter of distal section 12 a of shaft 12. In one embodiment,providing a tapered sleeve 18 allows for a desired compression betweenbone fragments without having to screw sleeve 18 into the bone. In oneembodiment, shaft 12 and sleeve 18 are configured to allow the distalend of sleeve 18 to abut against the beginning of first external malescrew thread 14.

In one embodiment, sleeve 18 includes two or more externallongitudinally extending slots 18 c that are configured to engage a toolas discussed below. In other embodiments, sleeve 18 may include aninternal hex, slot, projection, Torx or Phillips shape for receiving thetool. In one embodiment, sleeve 18 includes two or more radiallyextending projections 18 d. In one embodiment, radially extendingprojections 18 d act as a screw head to engage a bone surface. In otherembodiments, sleeve 18 does not include radially extending projections18 d and is instead configured to be completely countersunk into thebone and generally flush with the outer bone surface. In one embodiment,projections 18 d are countersunk into the bone. In one embodiment,sleeve 18 remains at the outer surface of the bone.

In one embodiment, screw device 10 is comprised of biocompatiblematerials. In one embodiment, screw device 10 is comprised ofbiocompatible metal, such as stainless steel or titanium. In oneembodiment, screw device 10 is comprised of biocompatible polymer suchas PEEK.

Referring to FIGS. 2A-2D, a tool 22 may be used to implant screw device10. In one embodiment, tool 22 is an at least two piece design that hasan outer drive sleeve 24 a and an inner drive shaft 26 b. In oneembodiment, tool 22 is a three piece design with outer drive sleeve 24 aincluding a lock sleeve 28. In one embodiment, inner drive shaft 26 bmates with internal female screw thread 20 of sleeve 18 while drivesleeve 24 a engages slots 18 d of sleeve 18.

In one embodiment, tool 22 includes a first tool portion 24 and a secondtool portion 26. In one embodiment, first tool portion 24 is configuredto rotate sleeve 18 relative to shaft 12. In one embodiment, second toolportion 26 is configured to rotate the shaft and sleeve together.

Referring to FIGS. 3A-3C, in one embodiment, first tool portion 22includes an enlarged handle 24 b. In one embodiment, handle 24 isconfigured to be griped by a user's hand to torque first tool portion24. In one embodiment, driver sleeve 24 a extends axially from handle 24b. In one embodiment, second tool portion 22 includes an enlarged handle26 d. In one embodiment, drive shaft 26 b extends axially from handle 26d. In one embodiment, handle 26 d abuts handle 24 b when drive shaft 26b extends through drive sleeve 24 a. In one embodiment, handle 26 d isreleasably coupled to handle 24 b to prevent drive shaft 26 b fromrotating relative to drive sleeve 24 a during use. In one embodiment,second tool portion 26 includes an open bore 26 c. In one embodiment,the diameter of bore 26 c is equal to the diameter of bore 12 f. In oneembodiment, bore 26 c allows for a guide wire extending from screwdevice 10 to extend through tool 22.

In one embodiment, drive sleeve 24 a includes two or more axiallyextending projections corresponding to slots 18 d of sleeve 18. In oneembodiment, the axially extending projections are circumferentiallyspaced from one another such that this is an open space between eachprojection to form phalanges. In other embodiments, the projections ofthe drive sleeve 24 a do not have an open space in between but insteadproject radially inward from the surrounding drive sleeve 24 a. In oneembodiment, drive shaft includes an external male screw thread 12 c. Inother embodiments, drive shaft 26 b includes a mating surface other thana screw thread such as a hex, star, or Phillips. In one embodiment, thedistal end of drive shaft 26 b extends axially further than the distalend of drive sleeve 24 a in a first position and the distal end of drivesleeve 24 a extends axially further than the distal end of drive shaft26 b in a second position.

Referring to FIGS. 4A-4C, in one embodiment, a lock sleeve 28 isprovided on the outer surface of drive sleeve 24 a. In one embodiment,lock sleeve 28 is used to ensure that the distal phalanges of drivesleeve 24 a do not flex radially and out of engagement with sleeve 18.In one embodiment, once drive shaft 26 b and drive sleeve 24 a arecoupled to sleeve 18 in an initially engaged position (FIG. 4A), locksleeve 28 is at least partially slid over distal phalanges of drivesleeve 24 a in a fully engaged position (FIG. 4C).

Referring to FIGS. 3A-4C, in an exemplary method of use of screw device10, shaft 12 and sleeve 18 are inserted into the fractured bone togetherusing tool 22 coupled to sleeve 18. In one embodiment, the distal tip ofshaft 12 engages and is screwed into the distal fragment of thefractured bone. In one embodiment, both first tool portion 24 and secondtool portion 26 are rotated together such that shaft 12 is rotatedwithout advancing sleeve 18 relative to shaft 12. In one embodiment,once the shaft 12 is in place, second tool portion 26 is unscrewed fromsleeve 18 and at least partially withdrawn from first tool portion 24.First tool portion 24 including drive sleeve 24 a then rotates sleeve 18relative to shaft 12 advancing sleeve 18 distally axially along shaft12. The outer surface of sleeve 18 contacts a proximal bone fragment andas sleeve 18 is advanced along shaft 12, screw device 10 draws thedistal and proximal bone fragments together.

In one embodiment, sleeve 18 enters the proximal bone fragment and atleast partially countersinks itself In one embodiment, sleeve 18 iscompletely countersunk such that the proximal end of sleeve 18 is flushto the outer surface of the proximal bone fragment. In one embodiment,first tool portion 24 includes a torque gauge or a safety feature toprevent over compression of the bone fragments. In one embodiment, theexcess portion of shaft 12, extending proximally from sleeve 18 afterscrew device 10 has been compressed, is cut or broken off from theremainder of shaft 12. In one embodiment, shaft 12 includes one or morepoints of weakness such as a score line or divot to aid in breaking offthe excess portion of shaft 12. In one embodiment, the proximal end ofshaft 12 is generally flush with the proximal end 18 b of sleeve 18after removing the excess portion of shaft 12.

In procedures requiring a smaller diameter implant or other procedures,a wire rather than a screw may be preferred. Typically Kirschner wiresor K-wires are used to keep bone fragments in place in certaininstances. However, K-wires have a single diameter and do not allow foreffective compression.

Referring to FIGS. 5A-5B, a wire device 30 includes a threaded wire 32and a sleeve 38. In one embodiment, a distal tip of wire 32 engages thebone shaft and sleeve 38 is secured to wire 32 to compress one or morebone fragments together. The remaining wire may then be cut or brokenoff.

In one embodiment, a distal section 32 a of wire 32 includes an externalmale screw thread 34. In one embodiment, the major diameter of wire 32is approximately 1.3 mm. In one embodiment, external male screw thread34 is a double lead pitch. In one embodiment, a proximal section 32 b ofwire 32 includes an external male screw thread 36. In one embodiment,the major diameter of distal section 32 a is larger than the majordiameter of proximal section 32 b. In other embodiments, the majordiameters of the distal section 32 a and proximal section 32 b areequal. In one embodiment, the pitch of external male screw thread 34 islarger than the pitch of external male screw thread 36. In otherembodiments, the pitches of the external male screw threads 34, 36 areequal. In some embodiments, wire 32 includes a plurality of ribs inaddition to or in place of external male screw thread 36. In oneembodiment, the distal end of wire 32 is pointed. In other embodiments,distal end of wire 32 is blunt.

In one embodiment, sleeve 38 includes an internal female screw thread 38e configured to mate with the external male screw thread 36. In oneembodiment, sleeve 38 is configured to slide over the external malescrew thread 36 in a distal direction without rotating sleeve 38relative to wire 32 but not slide in the proximal direction similar to azip or cable tie. In one embodiment, sleeve 38 includes two or moreaxially extending slots 38 d to form two or more flexible phalanges 38g. In one embodiment, internal female screw thread 38 e is only on theflexible portion of sleeve 38. In one embodiment, a proximal section 38f of sleeve 38 is smooth and does not contain threads.

In one embodiment, a distal portion of sleeve 38 has a diameter equal toor small than the major diameter of distal section 32. In oneembodiment, distal end 38 a of sleeve 38 is tapered. In one embodiment,the outer diameter of at least a portion of the distal portion of sleeve38 is approximately equal to or smaller than the minor diameter ofdistal section 32 a of wire 32. In one embodiment, the tapered sectionof sleeve 38 is greater than the minor diameter of distal section 32 aof wire 32 and tapers toward distal end to a diameter less than theminor diameter of distal section 32 a of wire 32. In one embodiment,wire 32 and sleeve 38 are configured to allow the distal end of sleeve38 to abut against the beginning of external male screw thread 34.

In one embodiment, sleeve 38 includes two or more radially extendingprojections 38 c. In one embodiment, projections 38 c are toward theproximal end 38 b of sleeve 38. In one embodiment, projections 38 callow for a tool or hand to more easily grasp and rotate sleeve 38relative to wire 32. In one embodiment projection 38 c act as a screwhead and remain on the outer surface of the bone.

Referring to FIGS. 6A and 6B, in an exemplary method of use, wire device30 is inserted between at least a proximal bone fragment 40 and a distalbone fragment 42. In one embodiment, wire 32 is inserted using a wiredriver. In one embodiment, wire 32 is screwed into distal bone fragment42. In one embodiment, sleeve 38 is slid along wire 32 without rotatingsleeve 38 relative to wire 32 until sleeve 38 abuts the outer surface ofproximal bone fragment 40. In other embodiments, sleeve 38 is screwed toadvance sleeve 38 along wire 32. In embodiments where proximal section32 b of wire 32 includes threads, once sleeve 38 abuts bone, sleeve 38is rotated relative to wire 32 to draw distal bone fragment 42 andproximal bone fragment 40 together. In one embodiment, sleeve 38 iscountersunk into proximal bone fragment 40. In other embodiments,projections 38 c acts as a screw head to prevent sleeve 38 fromcompletely countersinking. In one embodiment, once sleeve 38 is move tothe desired position along wire 32, the remaining wire 32 c proximate tosleeve 38 is cut or bent off from the remainder of wire 32.

In one embodiment, wire device 30 is comprised of biocompatiblematerials. In one embodiment, wire device 30 is comprised ofbiocompatible metal such as stainless steel or titanium. In oneembodiment, wire device 30 is comprised of biocompatible polymer such asPEEK.

In certain bone fractures there is a need for a rod that will beflexible on insertion but can be converted to a rigid implant.

Referring to FIGS. 7-9B, a bone fixation device 50 is initially flexibleand can be stiffened after implanting into the body. Bone fixationdevice 50 may be sized and configured to secure any two bones or bonefragments together including long bones having an intramedullary canalsuch as the humerus, femur, tibia, radius or ulna. In one embodiment,bone fixation device 50 is a humeral nail for implanting into thehumerus.

Referring to FIG. 7, bone fixation device 50 includes a plurality ofrigid segments 54 that are moveable relative to one another in aflexible or implanting configuration (FIG. 9B) and are fixed relative toone another in a rigid or implanted configuration (FIG. 9A). In someembodiments, rigid means substantially unbending or stiff. In someembodiments, bone fixation device 50 and/or rigid segments 54 may bendslightly under extreme forces or due to material strength or machinedtolerances. However, in some embodiments, bone fixation device issubstantially stiffer in the implanted configuration than in theimplanting configuration such that bone fixation device 50 can bendduring implanting and be stiffened to provide support between bones orbone fragments once implanted.

In one embodiment, a distal end 50 a is configured to be coupled to afirst bone section and a proximal end 50 b is configured to be coupledto a second bone section once implanted. In one embodiment, distal end50 a is generally pointed. In one embodiment, proximal end 50 b is bentand the remainder of bone fixation device 50 is straight once implanted.In other embodiments, bone fixation device 50 is curved or any othershape in the rigid position to fit to a desired anatomy. In oneembodiment, a substantial length of bone fixation device 50 is flexiblein the implanting configuration. In other embodiments, only a portion ofbone fixation device 50 is flexible in the implanting configuration. Inone embodiment, the entire bone fixation device 50 is rigid in theimplanted configuration. In other embodiments, at least a portion ofbone fixation device 50 remains flexible in the implanted configuration.In one embodiment, bone fixation device 50 is comprised of biocompatiblematerials. In one embodiment, bone fixation device 50 is comprised ofbiocompatible metal.

In one embodiment, distal end 50 a includes one or more apertures 50 cconfigured to receive a fastener such as a pin or screw. In oneembodiment, apertures 50 c are perpendicular to one another. In oneembodiment, proximal end 50 b includes one or more apertures 50 d. Inone embodiment, apertures 50 d are perpendicular to one another. In oneembodiment, apertures 50 c, 50 d are approximately 2.4 mm toapproximately 3.5 mm in diameter.

Referring to FIGS. 8A and 8B, which shows bone fixation device 50 withrigid segments 54 removed, bone fixation device includes a flexible body52 secured to distal end 50 a and movably attached to the proximal end50 b (see FIGS. 9A and 9B). In one embodiment, body 52 is flexible alonga first plane and rigid along a second plane orthogonal to the secondplane. In one embodiment, body 52 is rectangular cross section. In oneembodiment, body 52 is wider than it is thick. In one embodiment, body52 is machined out of a single block of material. In one embodiment,body 52 is comprised of multiple pieces joined together with pins,threads or other methods.

In one embodiment, body 52 is threadably attached to a radiallyrotatable, axially fixed sleeve 56 in the proximal end 50 b. In oneembodiment, sleeve 56 is cylindrical in shape and includes a groove 56 bthat mates with a corresponding projection or pins in proximal end 50 bor vice versa. Sleeve 56 is configured to rotate relative to proximalend 50 b and groove 56 b and the corresponding projection from proximalend 50 b prevents sleeve 56 from moving axially relative to proximal end50 b. In one embodiment, body 52 includes an external male screw thread52 c. In one embodiment, sleeve 56 includes an internal female screwthread 56 b configured to mate with male screw thread 52 c. In otherembodiments, the threads 52 c, 56 b of body 52 and sleeve 56 arereversed. In one embodiment, a proximal end of sleeve 56 is configuredto mate with a tool to rotate sleeve 56 relative to proximal end 50 b.The proximal end of sleeve 56 may include any mating feature such ashex, slot, projection, Torx or Phillips shape for receiving the tool.

In one embodiment, body 52 includes at least one aperture 52 d. In oneembodiment, at least one aperture 52 d of body 52 aligns with at leastone aperture 50 d of proximal end 50 b in the rigid configuration. Inone embodiment, body 52 includes a slot 52 e configured to receive aprojection or pin 50 e (see FIGS. 9A and 9B). In one embodiment, pin 50e prevents proximal end from rotating relative to proximal end 50 b.

Referring to FIGS. 9A and 9B, in one embodiment, rigid segments 54 arecannulated rigid segments that surround body 52. Rigid segments 54 mayhave any cross sectional shape such as rectangular, triangular or oval.In one embodiment, rigid segments 54 are cylinders. In one embodiment,there is a space between the inner surface of the rigid segments 54 andat least a portion of body 52. In one embodiment, any space between theinner surface of the rigid segments 54 and body 52 is filled with amaterial and/or includes a drug.

In one embodiment, rigid segments 54 have a contiguous outer surface. Inone embodiment, rigid segments 54 include one or more apertures. In oneembodiment, each rigid segment 54 includes at least one projection thatmates with an indent of an adjacent segment. In one embodiment, eachrigid segment includes an axially extending mating feature to preventrigid segments 54 and proximal and distal ends 50 a, 50 b from rotatingrelative to one another in the rigid position.

In one embodiment, body 52 has a first length measured between distaland proximal ends 50 a, 50 b in the flexible configuration and a secondlength measured between distal and proximal ends 50 a, 50 b in the rigidconfiguration, the first length being greater than the second length. Inone embodiment, rigid segments 54 are spaced in a flexible configurationto allow body 52 to flex. In one embodiment, rotating sleeve 56 drawsbody 52 axially relative to proximal end 50 b causing distal end 50 a tobe closer to proximal end 50 b and each of the rigid segments 54 tocollapse and abut one another to form a rigid device.

It will be appreciated by those skilled in the art that changes could bemade to the exemplary embodiments shown and described above withoutdeparting from the broad inventive concept thereof. It is understood,therefore, that this invention is not limited to the exemplaryembodiments shown and described, but it is intended to covermodifications within the spirit and scope of the present invention asdefined by the claims. For example, specific features of the exemplaryembodiments may or may not be part of the claimed invention and featuresof the disclosed embodiments may be combined. Unless specifically setforth herein, the terms “a”, “an” and “the” are not limited to oneelement but instead should be read as meaning “at least one”.

It is to be understood that at least some of the figures anddescriptions of the invention have been simplified to focus on elementsthat are relevant for a clear understanding of the invention, whileeliminating, for purposes of clarity, other elements that those ofordinary skill in the art will appreciate may also comprise a portion ofthe invention. However, because such elements are well known in the art,and because they do not necessarily facilitate a better understanding ofthe invention, a description of such elements is not provided herein.

Further, to the extent that the method does not rely on the particularorder of steps set forth herein, the particular order of the stepsshould not be construed as limitation on the claims. The claims directedto the method of the present invention should not be limited to theperformance of their steps in the order written, and one skilled in theart can readily appreciate that the steps may be varied and still remainwithin the spirit and scope of the present invention.

I claim:
 1. A bone screw for drawing first and second bone fragmentstogether, comprising: a shaft having a distal section and a proximalsection, the distal section having a first external male screw threadand a minor diameter, the proximal section having a second external malescrew thread, a major diameter of the distal section being larger than amajor diameter of the proximal section; and a sleeve having an internalfemale screw thread configured to mate with the second male screwthread, a distal portion of the sleeve having an outer diameter, theouter diameter being equal to or smaller than the minor diameter of thedistal section of the shaft.
 2. The bone screw of claim 1, wherein thesleeve is configured to receive a tool to rotate the shaft and sleevetogether when the shaft is driven into a first bone fragment or rotatethe sleeve relative to the shaft to draw a second bone fragment towardthe first bone fragment.
 3. The bone screw of claim 1, wherein a pitchof the first external male screw thread is larger than a pitch of thesecond external male screw thread.
 4. The bone screw of claim 1, whereinthe distal portion of the sleeve is tapered.
 5. The bone screw of claim1, wherein the sleeve includes two or more external longitudinallyextending slots configured to engage a tool.
 6. The bone screw of claim1, wherein the distal portion of the sleeve is smooth. The bone screw ofclaim 1, wherein the shaft is cannulated.
 8. The bone screw of claim 1,wherein the shaft includes at least one aperture along a length of theshaft in fluid communication with a hollow center of the shaft.
 9. Thebone screw of claim 1, wherein the shaft includes a plurality ofapertures along a length of the shaft, the plurality of apertures beingin fluid communication with one another.
 10. A bone screw system fordrawing first and second bone fragments together, comprising: a bonescrew including: a shaft having a distal section and a proximal section,the distal section having a first external male screw thread, theproximal section having a second external male screw thread, a majordiameter of the distal section being larger than a major diameter of theproximal section; and a sleeve having an internal female screw threadengageable with the second male screw thread, the sleeve beingconfigured to receive a first tool for rotating the shaft and sleevetogether and a second tool for rotating the sleeve relative to theshaft; a tool including: a first tool portion configured to rotate thesleeve relative to the shaft; and a second tool portion configured torotate the shaft and the sleeve together.
 11. The bone screw system ofclaim 10, wherein the second tool portion includes a threaded distal endthat is engageable with the internal female screw thread and abuts theproximal section.
 12. The bone screw of claim 10, wherein the secondtool portion extends through the first tool portion when rotating theshaft and sleeve together and the second tool portion is withdrawn fromthe first tool portion when rotating the sleeve relative to the shaft.13. A wire device for drawing first and second bone fragments together,comprising: a wire having an external male thread; and a sleeve havingan internal female thread configured to mate with the external malethread.
 14. The wire device of claim 13, wherein the sleeve isconfigured to slide over the external male thread in a distal directionwithout rotating the sleeve relative to the wire.
 15. The wire device ofclaim 14, wherein the sleeve includes two or more axially extendingslots to form two or more phalanges.
 16. The wire device of claim 13,wherein the wire includes a distal section and a proximal section, thedistal section having a first external male screw thread, the proximalsection having a second external male screw thread, a major diameter ofthe distal section being larger than a major diameter of the proximalsection.
 17. The wire device of claim 16, wherein a pitch of the firstexternal male screw thread is larger than a pitch of the second externalmale screw thread.
 18. The wire device of claim 13, wherein the sleeveincludes two or more radially extending projections.
 19. The wire deviceof claim 13, wherein a distal portion of the sleeve has a diameter equalto or smaller than a minor diameter of the wire.
 20. The wire device ofclaim 13, wherein the sleeve is tapered.
 21. A method for drawing firstand second bone fragments together, comprising: screwing a wire havingan external male thread into a first bone fragment; sliding a sleevehaving an internal female thread configured to mate with the externalmale thread along the wire without rotating the sleeve relative to thewire to abut a second bone fragment; rotating the sleeve relative to thewire to draw the second bone fragment toward the first bone fragment, aproximal portion of the wire extending proximally from the second bonefragment and the sleeve; and cutting and removing the proximal portionof the wire from the remainder of the wire.
 22. A bone fixation devicecomprising: a distal end configured to attached to a first bone sectionand a proximal end configured to attached to a second bone section, aflexible body secured to the distal end and movably attached to theproximal end; and a plurality of cannulated rigid segments surroundingthe body, wherein the segments are spaced and allow the body to flexwhen the body is in a first position relative to the proximal end andwherein the segments abut and prevent the body from being flexed whenthe plate is moved from the first position to a second position relativeto the proximal end.
 23. The bone fixation device of claim 22, whereinthe body is flexible along a first plane and rigid along a second plane,the first plane being orthogonal to the second plane.
 24. The bonefixation device of claim 22, wherein the body has a rectangular crosssection.
 25. The bone fixation device of claim 22, wherein the body isthreadably attached to a radially rotatable, axially fixed sleeve in theproximal end.
 26. The bone fixation device of claim 22, wherein eachsegment includes a projection that mates with an indent of an adjacentsegment in the second position.
 27. The bone fixation device of claim22, wherein the segments are cylindrically shaped.
 28. The bone fixationdevice of claim 22, wherein the body includes at least one aperture andthe proximal end includes at least one aperture, the at least oneaperture of the body aligning with the at least one aperture of theproximal end in the second position.